Pilot shifting

ABSTRACT

In an example embodiment, a network node transmits secondary signal component of a combined wireless communication signal to a user equipment. The combined wireless communication signal includes the secondary signal component and a primary signal component. Secondary pilot resources of the secondary signal component are dynamically shifted relative to primary pilot resources of the primary signal component by an amount that is based on whether a current estimation procedure at the user equipment is a primary channel estimation procedure or a secondary channel estimation procedure. In a corresponding example embodiment, the user equipment receives the combined wireless communication signal with the dynamically shifted pilot resources. The user equipment estimates the primary channel in the primary channel estimation procedure and estimates the secondary channel in the secondary channel estimation procedure.

TECHNICAL FIELD

Some example embodiments presented herein may be directed towards amethod in a Base Station for the dynamic shifting of pilot resources inan overlay communications system. Some example embodiments may bedirected towards a method in an user equipment for the estimation ofchannels in an overlay communications system as a function of thedynamic shifting.

BACKGROUND

The use of mobile broadband (MBB) services is rapidly increasing in allregions of the world as a result of the ongoing transition from cellulartelephony to MBB. Mobile data surpassed voice during December 2009 andyearly traffic increases in the order of 200% to 300% have been measuredin real networks. This increase is predicted to continue.

Mobile operators now face the challenge of handling this immense trafficincrease in their networks. One trend in radio research and regulationis based on the observation that many legacy systems are not using theirspectrum very efficiently. While replanning of such legacy systems couldfree up spectrum for licensed mobile use, significant efforts inresearch, standardization, and regulation are being spent on findingways of getting higher spectrum utilization in these bands by means ofsecondary usage of said spectrum.

A secondary user in this context is an user which is not using thespectrum for its licensed purpose and has obligations to not causeharmful interference to the licensed, or primary, usage. The broadcastTV systems have become the prime target for secondary spectrum usage andregulatory bodies already have rules in place for secondary usage. Themain reasons for the interest in the TV spectrum are the stationary andpredictability characteristics of the TV transmitters as well as thehigh value of the TV spectrum bands.

The presence of secondary users implies some sharing of spectrum bandsbetween primary and secondary systems. The sharing of spectrum betweentwo systems is usually grouped into one of the following threecategories or approaches: (1) the overlay approach; (2) the underlayapproach; or (3) the interweave approach.

The underlay approach uses a very low power per unit of bandwidth suchthat the interference caused to the primary system is kept below adefined level denoted the interference temperature. This level could beon the order of, or below, the thermal noise.

The interweave approach is the primary-secondary spectrum sharingapproach. In this approach the signals of the secondary systems areorthogonalized to the primary signals in the time, frequency, and/orspatial domain(s). This can be achieved by, e.g., letting the secondarysystems communicate on time/frequency resources that are unused byprimary systems. Another type of interweave is spatial/frequencyorthogonalization where channels unused by the primary system at certainlocations can be used by secondary systems.

In the overlay approach the secondary system cooperates with the primarysystem and uses the same spectrum resources for its communication. Thiscan be achieved by, e.g., letting the secondary system forward theprimary signals while also transmitting secondary signals on the samecommunication resources. The approach involves interference managementby the secondary system where one possible mechanism is interferencecancellation at the secondary receivers in which the primary signal isdecoded, reconstructed and subtracted from the received signal whichthen, ideally, only contains the secondary signal.

Studies show that the channel estimation performance may be an importantparameter for the sharing of communication resources. For example, ifthe channel estimates are poor, the achievable secondary system SNRswill be very low. A straightforward implementation of a shared systemtransmitter just superimposes the secondary signals on the primarysignals without making any modifications of the signal design. Thisresults in the optimal channel estimation performance not beingachieved, which limits the performance of the secondary system.

SUMMARY

Thus, at least one object of some of the example embodiments herein maybe to provide an improved method of signaling transmission. Some exampleembodiments may be directed towards a method in a network node fortransmitting a combined wireless communication signal. The combinedwireless communication signal comprises a primary and a secondary signalcomponent. The network node is comprised in a Radio Network. The methodcomprises transmitting the secondary signal component to be received byan user equipment. The secondary signal component comprises secondarypilot resources that are dynamically shifted. The dynamic shifting isbased on a current estimation procedure.

Some example embodiments may be directed towards a method in an userequipment for estimating a primary and a secondary channel, wherein thesecondary channel is a subset of the primary channel. The user equipmentis comprised in a Radio Network. The method comprises receiving from anetwork node a combined wireless communication signal. The combinedwireless communication signal comprises primary and secondary signalcomponents, where the secondary pilot resources of the secondary signalcomponent are shifted based on a current estimation procedure. Themethod also comprises estimating the primary channel when the currentestimation procedure is a primary channel estimation procedure, andestimating the secondary channel when the current estimation procedureis a secondary channel estimation procedure.

Some example embodiments may be directed towards a network node fortransmitting a combined wireless communication signal, the combinedwireless communication signal comprises a primary and a secondary signalcomponent. The network node is comprised in a Radio Network. The networknode comprises a communications port that may be configured to transmitthe secondary signal component to an user equipment. The network nodealso comprises a shifting unit that is configured to dynamically shiftsecondary pilot resources of the secondary signal component based on acurrent estimation procedure.

Some example embodiments may be directed towards an user equipment forestimating a primary and a secondary channel, wherein the secondarychannel is a subset of the primary channel. The user equipment iscomprised in a Radio Network. The user equipment comprises acommunications port that is configured to receive from a network node acombined wireless communication signal. The combined wirelesscommunication signal comprises primary and secondary signal components,where secondary pilot resources of the secondary signal component areshifted based on a current estimation procedure. The user equipment alsocomprises an estimation unit that is configured to estimate the primarychannel when the current estimation procedure is a primary channelestimation procedure. The estimation unit is also configured to estimatethe secondary channel when the current estimation procedure is asecondary channel estimation procedure.

Thus, as described above, the example embodiments presented hereindescribe secondary system pilot resource shifting for improving channelestimation performance. For example, an amount of pilot resourceshifting of the secondary system may be selected in order to obtain adesired degree of overlap between the primary and secondary systempilots. This results in a decrease of interference cased by thesecondary and primary systems thereby improving the accuracy of thechannel estimations.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of the example embodiments, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe example embodiments.

FIG. 1 is a schematic of an overlay communications system, according tosome of the example embodiments;

FIG. 2 is a schematic of an overlay communications system comprising acognitive transmitter, according to some of the example embodiments;

FIG. 3 is a schematic of a Base Station, according to some of theexample embodiments;

FIG. 4 is a schematic of an user equipment, according to some of theexample embodiments;

FIG. 5 is a flow diagram depicting example operations for secondarychannel estimation which may be performed by the user equipment of FIG.4, according to some of the example embodiments;

FIGS. 6A and 6B are illustrative examples of common taps between twocommunication channels, according to some of the example embodiments;

FIG. 7 is a flow diagram depicting example operations for pilot resourceshifting which may be performed by the Base Station and/or the userequipment of FIG. 3 and FIG. 4, respectively, according to some of theexample embodiments;

FIG. 8 is a flow diagram depicting example operations for cognitivesignal transmission and channel estimation which may be performed by theBase Station and/or the user equipment of FIG. 3 and FIG. 4,respectively, according to some of the example embodiments;

FIG. 9 is a flow diagram depicting example operations for primarychannel estimation which may be performed by the Base Station and/oruser equipment of FIG. 3 and FIG. 4, respectively, according to some ofthe example embodiments; and

FIGS. 10A and 10B are illustrative example of signal suppression,according to some of the example embodiments.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particularcomponents, elements, techniques, etc. in order to provide a thoroughunderstanding of the example embodiments. However, the exampleembodiments may be practiced in other manners that depart from thesespecific details. In other instances, detailed descriptions ofwell-known methods and elements are omitted so as not to obscure thedescription of the example embodiments.

Introduction

FIG. 1 depicts an example of an overlay communication system. An overlaycommunication system is a system which utilizes spectrum sharing in thetransmission of wireless communications. An overlay system typicallyinvolves a primary and secondary communication system. In the exampleprovided by FIG. 1, the primary system may comprise a televisionbroadcast system. The television broadcast system may comprise anynumber of transmitters 101 that may be configured to transmit wirelesstelevision signals, X_(TV), (e.g., a primary signal component) on aprimary channel, h_(TV), 103. The primary channel may also be configuredto transmit secondary signal components from a secondary system, asexplained below.

In the example provided by FIG. 1, the secondary system may comprise amobile communication system. The mobile broadband communications systemmay comprise any number of transmitters or Base Stations 105 that may beconfigured to simultaneously transmit a combined wireless signal on asecondary channel, h_(SS), 107. The combined wireless signal maycomprise the wireless television signal, X_(TV), (e.g., the primarysignal component) as well as a wireless communication signal, X_(SS),(e.g., a secondary signal component).

Since the secondary channel, h_(SS), conveys both primary and secondarysignal components, the secondary channel may be considered a sub-set ofthe overall primary channel, h_(TV), as shown in FIG. 1. Therefore, thesecondary channel, h_(SS), and the primary channel, h_(TV), may comprisecommon sub-components.

It should be appreciated that the television broadcast and mobilebroadband systems are used merely as examples. The example embodimentsdisclosed herein may be applied to any system utilized for transmittingany form of wireless data known in the art.

FIG. 2 illustrates a cognitive overlay communications system. In thecognitive overlay communications system, cognitive secondary systemtransmitters 105A may be configured to transmit the primary signal andsecondary wireless signal simultaneously 201, as described in relationto FIG. 1. The cognitive secondary system transmitters 105A may also beconfigured to transmit the primary signal and secondary wireless signalaccording to a transmission pattern 203. An example of a transmissionpattern 203 may be an alternate transmission of the primary andsecondary signals, such that the primary and secondary signals are nottransmitted simultaneously. It should be appreciated that the alternatetransmission pattern need not occur during the entire duration of thetransmission, for example, transmission patterns may be applied duringpredetermined periods of transmission. It should be appreciated that anyother type of transmission pattern may be employed. For example, theprimary signal may be continuously transmitted while the secondarysignal is transmitted at predetermined time intervals.

A mobile device, for example user equipment 100, may be configured toreceive communications from transmitters belonging to both the primaryand secondary systems. The received signal may be represented, forexample, as follows:Y=H _(TV) X _(TV) +H _(SS) X _(SS) +E ₁ +H _(SS) E ₂ +N  (1)where Y is the combined received signal, X_(TV) is the primary signalcomponent (e.g., television broadcast signal), X_(SS) is the secondarysignal component (e.g., cellular communication signal), N is thermalnoise and interference, H_(TV) is the superposition of wireless channelsthat participate in the single-frequency broadcast of televisionsignals, H_(SS) describes the wireless channel experienced by the signaltransmitted from the secondary system, E₂ is the Error Vector Magnitude(EVM) noise generated by transmitters used to generate X_(SS) andX_(TV), and E₁ is the EVM noise generated by all other transmitters inthe overlay system and filtered by the channel.

After channel estimation, decoding, reconstruction, and cancellation ofthe primary television signal X_(TV), the residual signal becomes:Y _(SS)=(H ₁ −H _(est))X _(TV) +H _(SS) X _(SS) +E ₁ +H _(SS) E ₂+N  (2)where H_(est) denotes the estimated primary channel. It should be notedthat the primary signal remains due to imperfect channel estimation. Thechannel estimation performance (e.g., how similar H_(est) is to H_(TV))plays a role when it comes to evaluation of the achievable Signal toInterference plus Noise Ratio (SINR) of Y_(SS).

Thus, at least one object of some of the example embodiments herein maybe to provide an improved method of signaling transmission. Thetechnical effect of this object may be to provide improved channelestimations without greatly increasing the amount hardware components orsystem resources.

Specifically, some example embodiments presented herein may be directedtowards an improved channel estimation. Some example embodiments may beapplied to a Base Station and/or user equipment node. Some exampleembodiments may be applied to methods of primary and/or secondarychannel estimations. Some example embodiments may utilize pilot resourceshifting in conjunction with the primary and/or secondary channelestimations. It should be appreciated that the example embodiments maybe applied to other nodes in a Radio network.

The example embodiments will be further described below according to therespective sub-headings. First example configurations of a Base Stationand user equipment will be provided. Thereafter, some exampleembodiments directed towards secondary channel estimation will bedescribed. Thereafter, some example embodiment directed towards pilotresource shifting will be provided. Pilot resource shifting may berelated to a method of signal transmission which may be utilized forchannel estimations. Example embodiments directed towards cognitivetransmission will also be provided. Thereafter, some example embodimentsdirected towards primary channel estimation will be provided.

It should be appreciated that a primary channel estimation procedureherein refers to the primary channel being estimated and the secondarychannel may be estimated with use of the primary channel estimation(i.e., based on the primary pilot resources). A secondary channelestimation procedure refers to the use of secondary pilot resources toestimate the secondary channel.

Base Station Configuration

FIG. 3 provides an illustrative example of a Base Station network nodeconfiguration, according to some of the example embodiments. The BaseStation 101, 105, or 105A may comprise any number of communication ports307. The communication ports 307 may be configured to receive andtransmit any form of communications data 303 and 305, respectively. Itshould be appreciated that the Base Station 101, 105, or 105A mayalternatively comprise a single transceiver port. It should further beappreciated that the communication or transceiver port may be in theform of any input/output communications port known in the art.

The Base Station 101, 105, or 105A may further comprise at least onememory unit 309 that may be in communication with the communicationports 307. The memory unit 309 may be configured to store received,transmitted, and/or measured data of any kind and/or executable programinstructions. The memory unit 309 be any suitable type of computerreadable memory and may be of a volatile and/or non-volatile type.

The Base Station 101, 105, or 105A may also comprise a shifting unit 313that may be configured to shift pilot resources of the primary and/orsecondary signals. The Base Station 101, 105, or 105A may furthercomprise a suppression unit 315 that may be configured to suppress,puncture, and/or mute the transmission of the primary and/or secondarysignal components. The Base Station 101, 105, or 105A may also comprisea general processing unit 311.

It should be appreciated that the shifting unit 313, the suppressionunit 315, and/or the processing unit 311 may be any suitable type ofcomputation unit, e.g. a microprocessor, digital signal processor (DSP),field programmable gate array (FPGA), or application specific integratedcircuit (ASIC). It should also be appreciated that the shifting unit313, the suppression unit 315, and/or the processing unit 311 need notbe comprised as separate units. The shifting unit 313, the suppressionunit 315, and/or the processing unit 311 may be comprised as a singlecomputational unit or any number of units.

User Equipment Configuration

FIG. 4 provides an illustrative example of an user equipment networknode configuration, according to some of the example embodiments. Theuser equipment 100 may comprise any number of communication ports 407.The communication ports 407 may be configured to receive and transmitany form of communications data 403 and 405, respectively. It should beappreciated that the user equipment 100 may alternatively comprise asingle transceiver port. It should further be appreciated that thecommunication or transceiver port may be in the form of any input/outputcommunications port known in the art.

The user equipment 100 may further comprise at least one memory unit 409that may be in communication with the communication ports 407. Thememory unit 409 may be configured to store received, transmitted, and/ormeasured data of any kind and/or executable program instructions. Thememory unit 409 be any suitable type of computer readable memory and maybe of a volatile and/or non-volatile type.

The user equipment 100 may also comprise an estimation unit 413 that maybe configured to estimate the primary and/or secondary signals and/orthe primary and/or secondary communication channels. The user equipment100 may further comprise an evaluation unit 415 that may be configuredto determine common sub-components between the primary and secondarycommunication channels. The user equipment 100 may also comprise ageneral processing unit 411.

It should be appreciated that the estimation unit 413, the evaluationunit 415, and/or the processing unit 411 may be any suitable type ofcomputation unit, e.g. a microprocessor, digital signal processor (DSP),field programmable gate array (FPGA), or application specific integratedcircuit (ASIC). It should also be appreciated that the estimation unit413, the evaluation unit 415, and/or the processing unit 411 need not becomprised as separate units. The estimation unit 413, the evaluationunit 415, and/or the processing unit 411 may be comprised as a singlecomputational unit or any number of units. It should also be appreciatedthat the user equipment 100 may be a mobile phone, a Personal DigitalAssistant (PDA), or any other wireless communications network unitcapable to communicate with a base station over a radio channel.

Secondary Channel Estimation

Some example embodiments may be directed towards providing improvedsecondary channel estimations. In general, the secondary system channelestimate used for demodulation in the secondary system may be improvedby utilizing the channel estimate from the primary system. If theprimary signal is transmitted from multiple sources whereas thesecondary signal is transmitted from a single source also, exampleembodiments may be used to identify common sub-components in the primaryand secondary channel estimates, respectively, and utilize thisinformation to derive an improved secondary system channel estimate.

By design the primary system may have more power than the secondarysystem. Therefore, the channel estimate formed in the primary system maybe of higher quality and may be used in the secondary system. Thus, ifthe primary signal is transmitted by a single source, the channelestimate obtained in the primary system may be used and forwarded to thesecondary system receiver. Alternatively, the user equipment maycomprise a primary channel estimator which may forward the estimationinformation. The estimation may comprise an interpolation of the primarysystem channel estimate to make it compatible with the secondary system,e.g., if the primary and secondary systems are OFDM systems withdifferent time/frequency grids. It could also comprise an extrapolationif the secondary system utilizes a larger bandwidth or larger timeduration than the primary system. Alternatively, the channel estimatemay be parameterized and the parameterized model may be forwarded to thesecondary system.

Potentially the primary signal may be transmitted from multiple sources,e.g., neighbouring Base Stations in a Single Frequency Network (SFN) ora high tower TV transmitter. In this case the channels of the primaryand secondary systems are not identical. Therefore, the primary channelmay be a combination of the channel from the “other” primary systemtransmitters (those that are not also sending the secondary signal ofinterest) and the primary signal transmitter that is sending thesecondary signal of interest.

FIG. 5 illustrates a flow diagram that provides example operations whichmay be utilized by the user equipment network node 100 of FIG. 4 inproviding secondary channel estimation, using primary channelestimation, for a multiple source scenario.

Operation 500:

Some example embodiments directed towards improved secondary channelestimation may comprise an user equipment 100 receiving 500 from anetwork node (e.g., a Base Station 101, 105 or 105A) a combined wirelesscommunication signal (e.g., comprising primary and secondary signalcomponents) through at least a portion of the primary channel.

The receiving 500 may be provided via the communications port 407.Specifically, the communications port 407 is configured to receive fromthe network node (e.g., Base Station 101, 105 or 105A) the combinedwireless communication signal through at least a portion of the primarychannel.

Operation 500A:

Prior to the performance of any channel estimations, operations may alsocomprise the user equipment 100 sending 500A information to a networknode (e.g., Base Station 105 or 105A). The information may provide anindication of a current estimation procedure.

Such information may be used by a cognitive Base Station 105A indetermining the transmission pattern of the primary and secondarysignals. For example, if the user equipment 100 is under going a primarychannel estimation procedure, the Base Station 105A may utilize the sent500A information and transmit only the primary signal and the resourcesused for the primary channel estimation procedure. Similarly, if theuser equipment 100 is under going a secondary channel estimationprocedure, the Base Station 105A may utilize the sent 500A informationand transmit the secondary signal such that the interference from theprimary signal on the secondary pilot resources is reduced.

The information regarding the current estimation procedure may also beutilized for pilot resource shifting, which will be explained in greaterdetail below. For example, if the user equipment 100 is under going aprimary channel estimation procedure, the sent 500A information may beutilized by the Base Station 105 or 105A to maximize an overlap betweenpilot resources of the primary and secondary signals. It should beappreciated that the maximizing may comprise any overlap percentageabove a certain user programmable threshold. Similarly, if the userequipment 100 is under going a secondary channel estimation procedure,the Base Station 105 or 105A may utilize the sent 500A information andminimize an overlap between pilot resources of the primary and secondarysignals. It should be appreciated that the minimizing may comprise anyoverlap percentage below a certain user programmable threshold.

Operation 501:

Upon receiving the combined wireless communication signal, operations inthe user equipment 100 also comprise determining 501 an estimate of theprimary channel. The estimation unit 413 and/or processing unit 411 areconfigured to estimate the primary channel.

Operation 502:

In some example embodiments, the determining 501 of the estimation ofthe primary channel may further comprise the user equipment 100reconstructing 502 the primary signal component of the combined wirelesscommunication signal. The reconstruction 502 may be performed with theuse of the estimation unit 413 and/or the processing unit 411.

Operation 503:

The determining 501 operation may further comprise the user equipment100 re-estimating the primary channel using the reconstructed signal asa pilot resource. The operation of reconstruction 503 may be performedwith the use of the estimation unit 413 and/or the processing unit 411.

Re-estimation of the primary channel with the utilization of thereconstructed signal as a pilot resource may increase the accuracy ofthe primary channel estimation.

Operation 505:

After the determination 501 of the primary channel estimate has beenobtained, operations further comprise the user equipment 100 determining505 an estimate of the secondary channel. The estimation of thesecondary channel may be obtained with a reconstructed secondary signalcomponent. The reconstructed secondary signal component may be obtainedby subtracting the primary signal component from the received signal.The estimation unit 413 and/or the processing unit 411 is configured toestimate the secondary channel.

Operation 506:

Upon determining 505 the secondary channel, operations further comprisedetermining 506 at least one common sub-component (e.g., at least onecommon tap) between the estimations of the primary and secondarychannels. An evaluation unit 415 and/or the processing unit 411 isconfigured to determine the at least one common sub-component betweenthe estimations of the primary and secondary channels. A commonsub-component may be a portion of the primary and secondary channelswhich correspond or are similar.

Operation 507:

In determining 506 the at least one common sub-component, operations mayfurther comprise the operation of the user equipment 100 constructing507 a first and second time and/or frequency representation or any otherparameterized representation of the estimated primary and secondarychannel. The evaluation unit 415 and/or the processing unit 411 may beconfigured to perform the constructing 507.

Examples of time and frequency domain representations are provided inFIGS. 6A and 6B, respectively. In FIGS. 6A and 6B, the upper graphrepresents the estimated channel comprising the primary and secondarychannels, and the lower graph in 6A represents the secondary channel (inthis case represented as taps), whereas the lower graph in 6B shows boththe primary (excluding the secondary component) and secondary channelswhich together build up the joint channel, i.e., that is illustrated inthe upper graph. The x-axis of all the graphs in FIGS. 6A and 6Brepresent the time and frequency, respectively.

Specifically, FIG. 6A illustrates an example of a constructed timedomain representation comprising scatter responses of the estimatedprimary channel, H_(TV), 601A. FIG. 6A also illustrates an example of aconstructed time domain representation of the estimated secondarychannel H_(SS), 603A.

FIG. 6B illustrates an example of a constructed frequency domainrepresentation of the estimated primary channel, H_(TV), 601B. FIG. 6Balso illustrates an example of a constructed frequency domainrepresentation of the estimated secondary channel H_(SS), 603B.

Operation 508:

Once the time and/or frequency domain representations or any otherparameterized representation have been constructed 507, operations mayfurther comprise the user equipment 100 comparing 508 the first andsecond time and/or frequency domain representations or any otherparameterized representation. The comparing 508 may be performed by theevaluation unit 415 and/or the processing unit 411.

Operation 509:

The comparing 508 may aid in the user equipment 100 determining 509 atleast one similar delay component and/or a similar complex exponentialwaveform or any other similar parameter of the first and second timeand/or frequency representations, respectively. The determining 509 maybe performed by the evaluation unit 415 and/or the processing unit 411.

The common sub-component (e.g., common tap) may be determined bycomparing the time domain representation, or scatter responses, of theprimary channel, H_(TV), 601A with the time domain representation of thesecondary channel, H_(SS), 603A. As shown in FIG. 6A, a common tap maybe found where the primary and secondary time domain representations601A and 603A, respectively, are similar such as the taps marked by 605.

FIG. 6B illustrates an example of a common tap in the frequency domain.The two complex exponential waveforms on the bottom of FIG. 6Bcorrespond to channels of the secondary and primary system (excludingthe secondary component) respectively, as denoted in the legend. The sumof those two waveforms, depicted in the upper graph of FIG. 6Bcorresponds to the estimated primary channel. This waveform may becompared with the complex exponential waveform of the secondary channelto determine the common complex exponential waveform. The commonwaveform can be transformed to the time domain to yield the commontap(s), which is similar to what is illustrated in FIG. 6A.

The common sub-components may represent a portion of the estimatedchannel which stems from the transmitter which transmits the secondarysignal. It should be appreciated that in the determination of the commonsub-components, the common sub-component portions of the time orfrequency domain representations need not be identical. For example, acommon sub-component may be determined if the common sub-componentportions of the time or frequency domain representations are similarwith respect to a threshold percentage. The threshold percentage may bebased on any percentage of similarity and may further be userprogrammable.

Operation 510:

Operations further comprise the user equipment determining 510 anupdated estimation of the secondary channel based on the at least onecommon sub-component (e.g., at least one common tap). The channelestimation of the primary channel comprising the at least one commonsub-component can be used as estimate for the secondary channel forthose sub-components. The determining estimation unit 413 and/or theprocessing unit 411 is configured to update the estimate of thesecondary channel based on the at least one sub-component. For example,the secondary channel estimate may be obtained by taking the estimatedvalues from the primary channel of the at least one commonsub-component.

Therefore, as described above, an improved estimation of the secondarychannel may be provided by obtaining a more precise estimation of theprimary channel. According to some example embodiments this may beachieved with the use of the reconstructing 502 and re-estimation 503.Furthermore, estimations are further improved by utilizing commonsub-components 506 in the estimation of the secondary channel 510. Thus,relative interference and noise levels in the secondary channelestimation may be reduced.

Pilot Resource Shifting

Some example embodiments may be directed towards pilot resourceshifting. Pilot resource shifting may be applicable if the secondarysystem allows for pilot shifting in the time and/or frequency domain. Anexample of such a system is a Long Term Evolution (LTE) system where thepilot resources may be shifted in time and/or frequency. Presumablyoverlap between the pilot resources of the primary and secondary systemsmay be different based upon the pilot resource shifting in the secondarysystem. Thus, some example embodiments may be directed towards theoptimal shifting of pilot resources of the secondary system. It shouldbe appreciated that some example embodiments may also comprise pilotresource shifting of the primary system.

If the secondary system uses the channel estimate of the primary systemas described above the pilot shifting may be selected to maximize theoverlap between the pilots, assuming that the non-overlapping pilots ofthe secondary system are enough to give a rough estimate of thesub-components in the channel representation if needed (e.g., asexplained in operation 506). The overlapping pilots may then besuppressed since they will not be used (or will at least not be used fordecoding). The suppression may comprise puncturing or muting, which willbe described in greater detail below. This allows a larger portion ofthe secondary resources to be used for data.

The optimization of the pilot shifting is not a time critical parameterto compute since it may be part of configuration (e.g., can be computedoff-line). FIG. 7 illustrates a flow diagram depicting exampleoperations which are utilized in the Base Station 105 or 105A and theuser equipment 100 of FIGS. 3 and 4, respectively, in providing theshifting of pilot resources and estimation based on the shifting.

Operation 700:

The shifting of pilot resources comprises transmitting 700 from thenetwork node (e.g., Base Station 105 or 105A) the secondary signalcomponent to be received by an user equipment 100. The secondary signalcomponent comprises secondary pilot resources that are dynamicallyshifted. The dynamic shifting is based on a current estimationprocedure.

The communications port 307 is configured to transmit the secondarysignal component to an user equipment 100. A shifting unit 313 isconfigured to dynamically shift secondary pilot resources of thesecondary signal component based on a current estimation procedure.

Operation 701:

In this operation the network node (e.g., Base Station 105 or 105A) maydetermine 701 a value of the current estimation procedure. Thedetermining 701 may be performed by the shifting unit 313 and/or theprocessing unit 311.

Operation 702:

The operation of determining 701 may further comprise the operation ofthe network node (e.g., Base Station 105 or 105A) determining 702 thevalue of the current estimation procedure and thereafter sending saidvalue to the user equipment 100. The value of the current estimation maybe useful such that the user equipment 100 may have knowledge of how itshould perform channel estimation. Since the determining 702 occurswithin the network node, it is the network node which may dictate thevalue of the estimation procedure and the shifting of pilot resources.The operation of determining 702 may be performed by the shifting unit313 and/or the processing unit 311.

Operation 703:

The operation of determining 701 may comprise the operation of thenetwork node (e.g., Base Station 105 or 105A) obtaining 703 the value ofthe current estimation procedure from the user equipment 100. In such aninstance, it is the user equipment 100 which may dictate the currentestimation mode and the shifting of pilot resources. The operation ofobtaining 703 may be performed by the communications ports 307.

Operation 704:

Pilot resource shifting may also comprise the operation of dynamicallyshifting 704 the secondary pilot resources to provide a maximum overlapwith primary pilot resources of the primary signal component, e.g., whenthe current estimation procedure is a primary estimation procedure. Itshould be appreciated that the maximizing may comprise any overlappercentage above a certain threshold, wherein the threshold may be anuser programmable threshold of any value. The operation of shifting 704may be performed by the shifting unit 313 or the processing unit 311.

Operation 705:

Pilot resource shifting may also comprise the operation of dynamicallyshifting 705 the secondary pilot resources to provide a minimum overlapwith primary pilot resources of the primary signal component, e.g., whenthe current estimation procedure is a secondary channel estimationprocedure. It should be appreciated that the minimizing may comprise anyoverlap percentage below a certain threshold, wherein the threshold maybe an user programmable threshold of any value. It should further beappreciated that any other threshold may be employed. The operation ofshifting 705 may be performed by the shifting unit 313 or the processingunit 311.

Operation 706:

Pilot resource shifting may also comprise a number of operationsperformed within the user equipment 100, for example operations 706-711.Example operations may comprise the operation of the user equipment 100receiving 706 from a network node (e.g., Base Station 101, 105 or 105A)a combined wireless communication signal comprising primary andsecondary signal components. Secondary pilot resources of the secondarysignal component being shifted based on a current estimation procedure.

A communications port 407 is configured to receive from a network node(e.g., Base Station 101, 105 or 105A) a combined wireless communicationssignal comprising primary and secondary signal components, secondarypilot resources of the secondary signal component are shifted based on acurrent estimation procedure.

Operation 707:

Operations may also comprise determining 707 the value of the currentestimation procedure within the user equipment 100. The operation ofdetermining 707 may be performed by the estimation unit 413 or theprocessing unit 411.

Operation 708:

The operation of determining 707 may comprise the user equipment 100determining 708 the value of the current estimation procedure andsending said value to the network node. The network node may receive thesent value as described in relation to operation 703. The operation ofdetermining 708 may be performed by the estimation unit 413 or theprocessing unit 411.

Operation 709:

The operation of determining 707 may comprise the user equipment 100obtaining 709 the value of the current estimation procedure from thenetwork node. The value obtained from the network node may be providedas explained in relation to operation 702. The operation of obtainingmay be performed by the communications port 407.

Operation 710:

Operations further comprise the user equipment 100 estimating 710 thesecondary channel when the current estimation procedure is a secondarychannel estimation procedure.

The estimation unit 413 and/or the processing unit 411 are furtherconfigured to estimation the secondary channel when the currentestimation procedure is a secondary channel estimation procedure.

Operation 711:

Operations further comprise the user equipment 100 estimating 711 theprimary channel when the current estimation procedure is a primarychannel estimation procedure.

The estimation unit 413 and/or the processing unit 411 are furtherconfigured to estimation the primary channel when the current estimationprocedure is a primary channel estimation procedure.

Thus, as described above, the shifting of pilot resources may be usefulin providing optimized channel estimations. Specifically, during primarychannel estimation a maximum overlap of pilot resources may enable agreater number of secondary resources to be used for data. Duringsecondary channel estimation a minimum overlap of pilot resources mayreduce interference caused by the primary system on the secondary pilotresources.

It should be appreciated that the shifting of pilot resources may beprovided by a series of computer executable instructions stored on acomputer readable medium. The optimization of the pilot shifting is nota time critical parameter to compute since it is part of configuration(i.e., can be computed off-line). An example algorithm, or computerexecutable instructions, for computing an optimal pilot shift isoutlined below.

-   -   1 Decide the target pilot overlap (e.g., “maximum”, “minimum” or        somewhere in between (e.g., 30%)), alternatively define a        performance metric to optimize.    -   2 For each possible pilot shift i in the set S where S contains        all allowed pilot shifts, compute the pilot overlap        (alternatively the metric to optimize) and store it in O(i)        where O is an array.    -   3 Select the pilot shift i where O(i) corresponds best to the        target pilot overlap (where the performance metric is optimized)        decided in step 1.

It should be appreciated that the instructions provided above were doneso merely to provide an example. Any other form of instructions may beutilized.

Cognitive Transmission and Estimation

In some example embodiments, cognitive transmission and estimation maybe employed. FIG. 8 is a flow diagram depicting example operationsperformed by a network node (e.g., Base Station 105A) and the userequipment 100 for handling primary and secondary channels, wherein thesecondary channel is a sub-component of the primary channel, accordingto some of the example embodiments.

Operation 801:

Cognitive transmission and estimation may comprise a network node (e.g.,Base Station 105A) sending 801 combined wireless communication signalson the secondary channel, which is a subpart of the primary channel,according to a predetermined pattern. The communication ports 307 isconfigured to send combined wireless communication signals on thesecondary channel, which is a subpart of the primary channel, accordingto a predetermined pattern. Specifically, some example embodiments maycomprise an alternating between sending 801 combined wirelesscommunication signals and being quiet (e.g., not sending any signals atall) according to the predetermined pattern.

Operation 802:

Operations may also comprise a network node sending 802 control signalsto a cognitive user equipment 100, or an user equipment capable ofreceiving cognitive data, the control signals may comprise informationindicative of the predetermined pattern. The communications port 307 maybe further configured to send the control signals to a cognitive userequipment 100, where the control signals may comprise the predeterminedpattern. The sending 802 of control signals may be useful to the userequipment 100, as the user equipment may adjust its current estimationprocedure based on what is currently being sent.

Operation 803:

Cognitive transmission and estimation may also comprise an userequipment 100 receiving 803 combined wireless communication signals onthe primary and secondary channels according to a predetermined pattern.

The communications port 407 is configured to receive combined wirelesscombination signals on the primary and secondary channels according to apredetermined pattern. Specifically, some example embodiments maycomprise alternately receiving 803 combined wireless communicationsignals on the primary and secondary channels and the primary signalonly on the primary channel (from 101 since 105, 105 a is quiet).

Operation 804:

Operations may further comprise the operation of the user equipment 100estimating 804 the primary and secondary channels as a function of thepredetermined pattern. As described in relation to operation 802, theuser equipment may gain knowledge of the current signal beingtransmitted via the control signals. It should be appreciated that insome example embodiments, the user equipment 100 may be configured tosend a request to the network node that either the primary or secondarysignal be sent at any given time.

Thus, as described above, cognitive transmission and estimation mayprovide improved channel estimations such that when the primary orsecondary channel is being estimated, the secondary or primary signal,respectively, may not be transmitted from the cognitive transmitter,according to some example embodiments. Thus, channel estimationinterference may be reduced.

Primary Channel Estimation

As described above, in relation to equation (2), the channel estimationperformance (e.g., how similar H_(est) is to H) may play a role when itcomes to evaluation of the achievable Signal to Interference plus NoiseRatio (SINR) of Y_(SS). However, the overlaid secondary system may addinterference to the pilots of the primary system and therefore effectthe channel estimation. Thus, some example embodiments may be directedtowards increasing the primary system channel estimation performance bysuppressing the resources of the secondary system which overlaps withthe pilot resources of the primary system. In some example embodiments,suppression may comprise puncturing or muting of the pilot resources.

In an Orthogonal Frequency Division Multiplexing (OFDM) scenario, thismeans that no or little power may be allocated to the time and/orfrequency resources of the secondary system which overlap with the timeand/or frequency resources used for channel estimation (e.g., pilots, orreference symbols) in the primary system. According to some exampleembodiments, a margin could be introduced such that slightly largerresources are left empty in the secondary system. This may reduceleakage effects from the non-empty resources of the secondary system tothe pilot resources of the primary system. Leaving larger resourceregions empty may be useful if OFDM system parameters do not coincidesince then orthogonality between the two systems is not given.Potentially complete OFDM symbol(s) needs to be punctured or muted.

In the suppression of pilot resources, puncturing may be utilized.Puncturing may comprise the process or replacing resource elements witha zero element after rate matching resulting in empty regions. It shouldalso be appreciated that such empty regions may already be consideredduring rate matching, i.e. no information is mapped onto thoseresources. This process is referred to as muting. It should further beappreciated that a cancelling signal may be applied to the regions ofinterest, such that the applied canceling signal results in a reducedpower region.

FIG. 9 is a flow diagram illustrating example operations which may beperformed by a network node (e.g., Base Station 105 or 105A) and an userequipment 100 with regard to primary channel estimation, according tosome of the example embodiments.

Operation 900:

Primary channel estimation may comprise a network node (e.g., BaseStation 105 or 105A) transmitting 900 to an user equipment 100 thesecondary signal component according to a secondary transmission schemesuch that the secondary signal component at least partially overlapswith the primary signal component with respect to a signal domain.

The communications port 307 may be configured to transmit to the userequipment 100 the secondary signal component according to a secondarytransmission scheme such that the secondary signal component at leastpartially overlaps with the primary signal component with respect to asignal domain.

It should be appreciated that the signal domain may be a time,frequency, and/or code domain. It should also be appreciated that theprimary and secondary signal components may be transmitted with respectto a domain grid transmission scheme.

FIG. 10A illustrates an example of an overlapping signal transmissioncomprising primary and secondary signal transmission using a time andfrequency domain grid transmission. The primary signal may betransmitted according to a time-frequency primary grid 205. Thesecondary signal may be transmitted according to a time-frequencysecondary grid 207. As illustrated from FIG. 10A, the secondary domaingrid may comprise a secondary grid spacing which may be different from aprimary grid spacing of a primary domain grid transmission scheme. Anexample of a primary pilot resource 206 is also provided in FIG. 10A.

Operation 901:

Primary channel estimation also comprises the network nodesimultaneously suppressing 901 at least one portion of the secondarysignal component during the transmission of the primary signalcomponent. The suppression unit 315 and/or processing unit 311 areconfigured to suppress at least one portion of the secondary signalduring a transmission of the primary signal component

FIG. 10B provides an example of signal suppression. In the center of theprimary grid 205 an ‘X’ 206 represents a pilot resource symbol. As shownin FIG. 10B, portions of the secondary grid which overlap with the pilotresources of the primary grid 205 may be suppressed (denoted in FIG. 10Bas shaded areas). Thus, as the primary channel is being estimated (e.g.,with the utilization of the primary pilot resources 206), anyinterference from the secondary system may be greatly reduced due to thesuppression. It should be appreciated that while FIGS. 10A and 10Billustrate the use of a time-frequency grid, any type of grid in thetime, frequency, or code domain may be employed.

Operation 902:

As described above, the suppression may comprise the network nodepuncturing or muting 902 the at least one portion of the secondarysignal component which overlaps with pilot resources of the primarysignal component. The operation of puncturing or muting 902 may beperformed by the suppression unit 315 and/or the processing unit 311. Itshould be appreciated that the puncturing or muting may be performedtogether with a cancelling signal such that once the cancelling signalis combined with the secondary signal; the combined signal mayexperience a reduced (e.g., zero or close to zero) amplitude in thepredetermined grid cells.

Operation 903:

Operations may further comprise the network node suppressing 903 atleast one region of the secondary domain grid. The operation ofsuppression 903 may be performed by the suppression unit 315 and/or theprocessing unit 311.

As shown in FIG. 10B, in some example embodiments for any portion of thesecondary grid 207 which overlaps with the primary pilot resource ‘X’206, an entire region of the grid cell may be suppressed. For example,only a portion of the secondary grid cell 208 overlaps with the pilotsymbol 206. However, in some example embodiments the entire region ofthe secondary grid cell 208 may be suppressed in order to improve theprimary channel estimation performance. Similarly, in some exampleembodiments, an entire region of a secondary grid cell 210 may besuppressed even if the cell does not overlap with the primary pilotresource 206. Specifically, secondary grid cells surrounding or in closeproximity to the primary pilot resource may be suppressed as well.

Operation 904:

Operations may further comprise the network node being a secondarytransmitter and the secondary transmitter obtaining 904 informationregarding a transmission pattern of a pilot resource of the primarysignal component. A secondary transmitter may be a secondary systemtransmitter which solely transmits the secondary communication signal.The operation of obtaining 904 may be performed by the communicationsport 307 and/or the processing unit 311.

Operation 905:

The operation of obtaining 904 may further comprise the secondarytransmitter suppressing 905 the at least one portion of the secondarysignal component as a function of the information. The operation ofsuppressing 905 may be performed by the suppression unit 315 and/or theprocessing unit 311 of the secondary transmitter.

Operation 906:

Operations may further comprise an user equipment 100 receiving 906 acombined wireless communication signal. The primary and secondary signalcomponents being received according to a primary and secondarytransmission scheme associated with a primary and secondary signaldomain, respectively.

The communications port 407 is configured to receive from a network node(e.g., Base Station 105 or 105A) a combined wireless communicationsignal comprising primary and secondary signal components, the primaryand secondary signal components being received according to a primaryand secondary transmission scheme, associated with a primary andsecondary signal domain.

Operation 907:

Operations also comprise an user equipment 100 estimating 907 theprimary channel when the secondary signal component is suppressed. Theestimation unit 413 and/or processing unit 411 are configured toestimate the primary channel during a period when the secondary channelis suppressed.

Operation 908:

The operation of estimating 907 may comprise the User Equipment 100estimating 908 the primary channel during a period when the at least oneportion of the secondary signal component overlaps with a pilot resourceof the primary signal component. For example, even if only a smallportion of a grid cell overlaps with the pilot resource, an entireregion of the grid cell of the secondary signal may be suppressed, asexplained in relation to operation 903. The operation of estimating maybe performed by the estimation unit 413 and/or the processing unit 411.

Thus, as described above, primary channel estimation may be improvedwith the use of suppression, according to some example embodiments. Theuse of suppression may reduce interference during estimation.

Conclusion

Some example embodiments may comprise a portable or non-portabletelephone, media player, Personal Communications System (PCS) terminal,Personal Data Assistant (PDA), laptop computer, palmtop receiver,camera, television, radar and/or any appliance that comprises atransducer designed to transmit and/or receive radio, television,microwave, telephone and/or radar signals. The device according to theexample embodiments is however intended for use particularly, but notexclusively for high frequency radio equipment.

The foregoing description of the example embodiments, have beenpresented for purposes of illustration and description. The foregoingdescription is not intended to be exhaustive or to limit exampleembodiments to the precise form disclosed, and modifications andvariations are possible in light of the above teachings or may beacquired from practice of various alternatives to the providedembodiments. The examples discussed herein were chosen and described inorder to explain the principles and the nature of various exampleembodiments and its practical application to enable one skilled in theart to utilize the example embodiments in various manners and withvarious modifications as are suited to the particular use contemplated.The features of the embodiments described herein may be combined in allpossible combinations of methods, apparatus, modules, systems, andcomputer program products.

It should be noted that the word “comprising” does not necessarilyexclude the presence of other elements or steps than those listed andthe words “a” or “an” preceding an element do not exclude the presenceof a plurality of such elements. It should further be noted that anyreference signs do not limit the scope of the claims, that the exampleembodiments may be implemented at least in part by means of bothhardware and software, and that several “means”, “units” or “devices”may be represented by the same item of hardware.

A “device” as the term is used herein, is to be broadly interpreted tocomprise a radiotelephone having ability for Internet/intranet access,web browser, organizer, calendar, a camera (e.g., video and/or stillimage camera), a sound recorder (e.g., a microphone), and/or globalpositioning system (GPS) receiver; a personal communications system(PCS) terminal that may combine a cellular radiotelephone with dataprocessing; a personal digital assistant (PDA) that can comprise aradiotelephone or wireless communication system; a laptop; a camera(e.g., video and/or still image camera) having communication ability;and any other computation or communication device capable oftransceiving, such as a personal computer, a home entertainment system,a television, etc.

The various example embodiments described herein is described in thegeneral context of method steps or processes, which may be implementedin one aspect by a computer program product, embodied in acomputer-readable medium, including computer-executable instructions,such as program code, executed by computers in networked environments. Acomputer-readable medium may comprise removable and non-removablestorage devices including, but not limited to, Read Only Memory (ROM),Random Access Memory (RAM), compact discs (CDs), digital versatile discs(DVD), etc. Generally, program modules may comprise routines, programs,objects, components, data structures, etc. that perform particular tasksor implement particular abstract data types. Computer-executableinstructions, associated data structures, and program modules representexamples of program code for executing steps of the methods disclosedherein. The particular sequence of such executable instructions orassociated data structures represents examples of corresponding acts forimplementing the functions described in such steps or processes.

The invention claimed is:
 1. A method in a network node for transmittinga combined wireless communication signal, wherein the combined wirelesscommunication signal comprises a primary and a secondary signalcomponent, the network node is configured for operation in a radionetwork, and the method comprises: shifting secondary pilot resources ofthe secondary signal component relative to primary pilot resources inthe primary signal component by an amount that is based on whether acurrent estimation procedure at a user equipment is a primary channelestimation procedure or a secondary channel estimation procedure;transmitting the secondary signal component to be received by the userequipment.
 2. The method of claim 1, wherein the network node is a BaseStation.
 3. The method of claim 1, further comprising determiningwhether the current estimation procedure is the primary channelestimation procedure or the secondary channel estimation procedure andsending a corresponding value to the user equipment, to indicate to theuser equipment whether the current estimation procedure is the primarychannel estimation procedure or the secondary channel estimationprocedure.
 4. The method of claim 1, further comprising obtaining avalue from the user equipment and determining from the value whether thecurrent estimation procedure is the primary channel estimation procedureor the secondary channel estimation procedure.
 5. The method of claim 1,wherein, for the case where the current estimation procedure is theprimary channel estimation procedure, shifting the secondary pilotresources comprises shifting the secondary pilot resources so as toprovide a maximum overlap with the primary pilot resources of theprimary signal component.
 6. The method of claim 1, wherein, for thecase where the current estimation procedure is the secondary channelestimation procedure, shifting the secondary pilot resources comprisesshifting the secondary pilot resources so as to provide a minimumoverlap with the primary pilot resources of the primary signalcomponent.
 7. The method of claim 1, wherein the primary signalcomponent is a broadcast communication signal.
 8. The method of claim 1,wherein the secondary signal component is a broadband communicationsignal.
 9. A method in a user equipment for estimating a primary and asecondary channel, wherein the secondary channel is a subset of theprimary channel, wherein the user equipment is configured for operationin a radio network and the method comprises: receiving from a networknode a combined wireless communication signal comprising primary andsecondary signal components, wherein secondary pilot resources of thesecondary signal component are shifted relative to primary pilotresources of the primary signal component by an amount that is based onwhether a current estimation procedure is a primary channel estimationprocedure or a secondary channel estimation procedure; estimating theprimary channel when the current estimation procedure is the primarychannel estimation procedure; and estimating the secondary channel whenthe current estimation procedure is the secondary channel estimationprocedure.
 10. The method of claim 9, wherein the network node is a BaseStation.
 11. The method of claim 9, wherein the user equipmentdetermines whether the current estimation procedure is the primarychannel estimation procedure or the secondary channel estimationprocedure, and sends a corresponding value to the network node.
 12. Themethod of claim 9, further comprising obtaining a value of the currentestimation procedure from the network node, which value indicates to theuser equipment whether the current estimation procedure is the primarychannel estimation procedure or the secondary channel estimationprocedure.
 13. The method of claim 9, wherein the secondary pilotresources have a maximum overlap with primary pilot resources of theprimary signal component for the primary channel estimation procedure.14. The method of claim 9, wherein the secondary pilot resources have aminimum overlap with primary pilot resources of the primary signalcomponent for the secondary channel estimation procedure.
 15. The methodof claim 9, wherein the primary signal component is a broadcastcommunication signal.
 16. The method of claim 9, wherein the secondarysignal component is a broadband communication signal.
 17. A network nodefor transmitting a combined wireless communication signal, the combinedwireless communication signal comprising a primary and a secondarysignal component, wherein the network node is configured for operationin a radio network and comprises: a communications port configured totransmit the secondary signal component to a user equipment; and aprocessing circuit configured to shift secondary pilot resources of thesecondary signal component relative to primary pilot resources of theprimary signal component by an amount that is based on whether a currentestimation procedure at the user equipment is a primary channelestimation procedure or a secondary channel estimation procedure. 18.The network node of claim 17, wherein the network node is a BaseStation.
 19. The network node of claim 17, wherein the primary signalcomponent is a broadcast communication signal.
 20. The network node ofclaim 17, wherein the secondary signal component is a broadbandcommunication signal.
 21. A user equipment for estimating a primary anda secondary channel, wherein the secondary channel is a subset of theprimary channel and the user equipment is configured for operation in aradio network and comprises: a communications port configured to receivefrom a network node a combined wireless communication signal comprisingprimary and secondary signal components, wherein secondary pilotresources of the secondary signal component are shifted relative toprimary pilot resources of primary signal component by an amount that isbased on whether a current estimation procedure is a primary channelestimation procedure or a secondary channel estimation procedure; aprocessing circuit configured to estimate the primary channel when thecurrent estimation procedure is the primary channel estimationprocedure, and to estimate the secondary channel when the currentestimation procedure is the secondary channel estimation procedure. 22.The user equipment of claim 21, wherein the network node is a BaseStation.
 23. The user equipment of claim 21, wherein the primary signalcomponent is a broadcast communication signal.
 24. The user equipment ofclaim 21, wherein the secondary signal component is a broadbandcommunication signal.